With the enhancement in the quality of multimedia contents, a high quality multichannel audio signal, such as a 7.1 channel audio signal, a 10.2 channel audio signal, a 13.2 channel audio signal, and a 22.2 channel audio signal, having a relatively large number of channels compared to an existing 5.1 channel audio signal, has been used. However, in many cases, the high quality multichannel audio signal may be listened to with a 2-channel stereo loudspeaker or a headphone through a personal terminal such as a smartphone or a personal computer (PC).
Accordingly, binaural rendering technology for down-mixing a multichannel audio signal to a stereo audio signal has been developed to make it possible to listen to the high quality multichannel audio signal with a 2-channel stereo loudspeaker or a headphone.
The existing binaural rendering may generate a binaural stereo audio signal by filtering each channel of a 5.1 channel audio signal or a 7.1 channel audio signal through a binaural filter such as a head related transfer function (HRTF) or a binaural room impulse response (BRIR). In the existing method, an amount of filtering calculation may increase according to an increase in the number of channels of an input multichannel audio signal.
Accordingly, in a case in which an amount of calculation increases according to an increase in the number of channels of a multichannel audio signal, such as a 10.2 channel audio signal and a 22.2 channel audio signal, it may be difficult to perform a real-time calculation for playback using a 2-channel stereo loudspeaker or a headphone. In particular, a mobile terminal having a relatively low calculation capability may not readily perform a binaural filtering calculation in real time according to an increase in the number of channels of a multichannel audio signal.
Accordingly, there is a need for a method that may decrease an amount of calculation required for binaural filtering to make it possible to perform a real-time calculation when rendering a high quality multichannel audio signal having a relatively large number of channels to a binaural signal.